Dry and swollen thicknesses in Milli-Q water of polymer brushes, prepared with different catalyst concentrations and 1 : 1 HEMA/water mixture, as measured by both AFM and ellipsometry at room temperature.

Catalyst conc. (%)	AFM (dry thickness, nm)	AFM (swollen thickness, nm)	Ellipsometry (dry thickness, nm)	Ellipsometry (swollen thickness, nm)	AFM swelling ratioa	Ellipsometry swelling ratioa
40	22	27	30 ± 2	57 ± 4	1.2	1.9
70	46	61	55 ± 3	88 ± 3	1.3	1.6
100	48	60	58 ± 4	87 ± 5	1.3	1.5

^aSwelling ratio defined as T_swollen/T_dry.